Recently, a cooling apparatus using the air as a refrigerant has been developed in place of a conventional cooling apparatus using chlorofluorocarbon as a refrigerant.
Japanese Laid Open Patent Application JP-A-Heisei 11-132582 discloses an air refrigerant type freezing apparatus having a compressor, an air cooler, an air-to-air heat exchanger, and an expansion unit arranged in an order of an air flow, taking air of a chamber required to be cooled into the compressor through the air-to-air heat exchanger, and blowing off the air outputted from the expansion unit into the chamber, characterized by including a first bypass provided with a valve for returning a part of or all of the air from the expansion unit to the air-to-air heat exchanger while bypassing the chamber, and a hot air bypass provided with a valve for taking in the air at 0° C. or higher from an air passage between the compressor and the expansion unit, and for supplying the air to an air passage on an inlet side of the air-to-air heat exchanger.